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Abstract
Heme is an essential cofactor for the vast majority of organisms, required for numerous biological reactions, and its biosynthesis is a complex process. Three heme biosynthetic pathways have been identified, with the most recent being the coproporphyrin dependent (CPD) pathway. Prior to the identification of the CPD pathway, it was thought that bacteria, with very few exceptions, required the formation of protoporphyrin IX for heme biosynthesis. However, identification of the CPD pathway correctly assigned the true function of two enzymes and identified the missing enzyme as coproheme decarboxylase (ChdC). In the CPD pathway, coproporphyrinogen III is oxidized to coproporphyrin, followed by iron insertion into the tetrapyrrole, forming coproheme. The final step of the CPD pathway is the decarboxylation of coproheme to heme by ChdC. The CPD pathway is exclusively found in firmicutes and actinobacteria, both of which are pathogenic and highly antibiotic resistant bacteria that contribute to human disease. The investigation into the mechanism of the penultimate enzyme in the CPD pathway, ChdC, will assist in the development of new antimicrobial compounds.